Method of making projectiles



May 4, 1 9 48. 1', HURLEY I 2,440,952

ammo OF MAKING PROJECTILES Original FiledApril 16, 1938 INVENTOR.

Patented May 4, 1948 MEIBQDP mereowwwse B011 Hurley; Westport, Conn, assignor. to Bendix Aviation.CorporationgSiiuthBend, Iildi," a.corporatiofiio{Delaware Original application- April 16", 1938,v Serial N02.

202,399; Divided "and this? applicationiJulyi 297,. 1942,Serial,l\lo. 452,709

1 Claim (01. 2.2 1 29%) compressive pressure: to: reduce; the diameter of a ne nd-wn prmthe ame; w h ha e o the groove. The highpres ure'which islnecessarail-y applied tozconf ormt thelsof t metal band, to. the shapeof; thegroove distortsthemetalandsets up; internal stresses within the-fih-ished;rotating band. hich t n t-t e s n-ih x ama Of e fsulto hi -w aknesses e a i: ie-d s; compression. of. the metal. rihg to completely fill: the groove, the joint between the projecti-le blank and the rotating band.is, not.gasvtiglt Accordingl-y, gasleakage, frequently occurs; between the band. and-the projectilewhen. the same are fired. from; a gun, thereby decreasing the efficiency of theaexplosivecharge; and. causing the projectile to; fall shortof its in-tende dqtarget; Furthermore, the leakageaof; the high-pressure gases oiexplosion between the. rotating band and the projectile tendstoloosenthe for-mer tolsuchan extent that, the; same will bethrown from the projectile by centrifugal forces acting thereon as the rapidly rotating shell l'eaves that The loss of the rotating, band affects the trajectory of the profor carryihg oiitthenovel .znetnod comprehended:

by; the; invention, saidmeans. being. so. constituted asJJQ.

' tating band thereto,

' drawings.

The above andifiirther objects and; novel. features ofthe invention will .niore fully, appear from the f ollowing detailed description, when, the same is taken; in corinect'ion} with the. accompanying, to be expressly understoo'd'fhowever, -that', the drawin s ar'e'for' thepurDOSe ofv illustration. only andiarenot. designed "as a, defini-J tion smi e limits-dither inventi dmjreierencebeing' mime jury, was we, p r qse to; 25-

pen claim;

.ln the drawings, wherein like reference characviews,

Fig, 1 is alongitudinalsectional View taken substantially amne n eam. oflEig, 1;..'and;.

Big 3. is a plan. view of a completed projectile. 2th.. the illustrated Y embodiment; one "form of means suitable for carryihgput theno'vel, process ofthevinvention. is shown a s-comprising" a mold which com ,letely,encirclfes a. portion of. the pro-' jectile' and, in addition,imperilsffthepersonnel.

in the vicinity of the gun. Because of the necessity for distorting. the metaliof the rotating band in the methods heretofore employed, the hardness. andtypesot metals which "may .be employed in practicingsaid methods is undi ly restrictedl Accordingly, one ofthe ohjects' of they present invention isito provide a'novelfmethod rorappi meet rotating band to a projectile-in suchla inannferdthat the foregoing disadvantages arejcbllia, e

Another object oi the inventionv is to provide a novel method for applying; a rotating band; to a projectile whereby saidhandf is caused to become, imeiiect, anintegralpart ofith projectile."

A; u erb ec s. temoi de ane methedef e p s a at n bend t a ro le. whi method permits of the use of metals having a wider range of properties such as hardnfifis, ductility, melting point, etc.

ie til? blam -W 6 latter on opposite e providedinsaid; blank for p0Sitio ingv a rotating band 1 (Fig. 3). Molddis'provid'edwith a groove awhich. is adaptedto register andcooperatewith grooveffito form ah annular channeljoijthe' same siae Y andl shape as the desired rotating band 1..

engages the periphery of the Mold 4; is preferably split along the extension of a, horizontal: diameter 01. projectile 5, into two I separable sections llaandlh theiformer; as shown,

be n e upper section and aving. a runn r or cupr hap dl ins it herem, h c mu Gates. withthe channel; formedbygrooves S and 8, Means are-provided.fortightly dampmg mold section-si ica andfib to each; otheraround projectile. 5: and. in the: ill-ustrated embodiment said; means. comprise a.- pair Off arms to, and H. (Fig. 2-) pivotally secured to opposite "sides of section 4b by"means=of pins: [2. and. v arms are adapted to; pivot, the directiorr of section' lai and. to have the free. ends thereof. extends. over" slightlyconcaved shoulders l-, 4= formed on; opposed sides of said section. Cam levers I5 and 16 are pivotally secured to the free ends of arms Still another ob i'ect istol provide novel means compe sa e. for. the, thermal expansion of r 'ectile. during application. of the; rogters refer to likei'parts throughout severalij sides of. an annular groove 6,

[3, respectively. Said by the present invention for applying rotating band 1 to projectile blank 5, the latter is first positioned in mold 4 so thattheedgesof groove 6 coincide with or are suitably positioned relative to the edges of groove 8. Arms 10 and H are pivoted in the direction of section do until the cam surfaces of levers l and "Bare directly over shoulder l 4 and then said levers are pivoted upwardly and inwardly to cause a pressure to be applied to shoulders l4, thereby clamping section 4a to section 4b. A metallic slug H from which rotating band I is to beformed is then inserted into opening or conduit 9 and the whole is placed. in' a furnacehaving a reducing atmosphere, such as in a hydrogen furnace. The temperature within the furnace is then raised until slug l1 melts and the molten metal flows into the channel'forined by grooves 6 and 8. The metal, preferably a copperalloy, from which slug I] is made, isso chosen that when the same is in amolten state, it will wet the surfaces 'of grodveIBJ. Thus,.vvhen the mold and projectile blank -are permittedto cool, the rotating band is castin'place and fused to thesteel projectile so as toform' an integral part'thereof. It will be understood that groove 6 may be dovetailed, if desired, but this is not necessary to secure an adequate bond between the band. and projectile when practicing the method of the present invention.

. Slug ll which is preferably composed of copper or. a copper alloy-determines the composition of mold 4 since the latter must be formed from, or at least coated with, a metal, such as stainless steel, which will not be wet by the metal constituting the slug when the latter is in a molten state. Inother words, mold4 must be formed from a metal which will not fuse with the copper orother suitable metal of slug I! in the reducing atmosphere of the furnace. Accordingly, when the liquefied metal flows into channel 6-8, it will become fused or brazed only to the surface of groove, 6, thereby rigidly fixing the subsequently solidifiedband 1 to projectile 5 and permittingfthe ready removal of mold sections 41: and 412 after solidification.

' In order to insure against any possible leakage of the molten, metal between the engaging surfaces of mold 4 and shell body 5 the former is madepf metal which preferably has a coefficient of thermal expansion equal to or slightly less than the coefficient of thermal expansion of body 5. It has been determined that, if the projectile is. made of a mild steel having a coefiicient of thermal expansion of about .0000063 inch per degree Fahrenheit, for example, the mold may be made of, a-stainless steel commercially known as Carpenter No.2 which has a chromium content of from 12 to 14 per cent and a carbon content of .3 per cent and which has a coefficient of thermal expansion'of about .0000056 inch per degreeFahrenheit. A suitable metal which may be employed in making the mold is commercially known as Firth Sterling AA and is a stainless steel having a chromium content of from 13 to 14 per cent and a very low carbon content and having a coeflicient of thermal expansion of about .0000059 inch per degree Fahrenheit. To further insure against leakage ofthe molten metal, the surfaces of mold which are in contact with the periphery of projectile 5,and the surfaces of sections 4a and 4b which engage each other when said sections are clamped in operative position-may be coated or plated with a silicate of soda or a graphite paint. The inclusion of a .film .of said plating or paint between the contacting surfaces effectively prevents any leakageof the molten metal between said surfaces."

'There is thus provided a novel method for producing a novel projectile having a rotating band which is fused to the projectile body. The fusion of'band to body produces a firm bond therebetween and eliminates the possibility of leakage of gases of explosion between the band and the projectile body and the danger of said band being thrown from the shell by centrifugal forces. The eiliciency and accuracy of the firing is thereby increased and the dangers to the personnel are materially reduced.

Although only a single embodiment of this in vention has been illustrated and described, it is to be expressly understood that the same is not limited thereto, but that various changes may be made therein. For example, metals having properties difierent from those of copper or a copper alloy may be employed, if desired, for the rotating band and a metal other than stainless steel may be utilized in making the mold. Changes in the design and arrangement of parts may also be'made without departing from the spirit and scope of the'invention, as willnow be understood by those skilled in the 'art. For a definition of the limits of theinvention, reference will be had primarily to the appended claim. What is'claimed is:

The method of applying an annular projecting rotating band to a projectile having a mild steel body that comprises sealing about the projectile a mold comprising high chromium stainless steel having an annular groove in register with the groove in the projectile, and filling the cooperating grooves with a molten metallic material comprising copper whereby there is formed a ring adherent to the projectile but not to the mold.

g ROY T. HURLEY.

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